The Inhibitory Effect Of Glycinin Antibacterial Peptide On Listeria Monocytogenes And Staphylococcus Aureus

Glycinin antibacterial peptide(GAP)is a natural antibacterial component from soybean protein.This study investigated the antibacterial properties of GAP against Listeria monocytogenes(L.monocytogenes)and Staphylococcus aureus(S.aureus).And evaluated the effect of GAP on the quality of Scomberomorus niphonius surimi(SNS)during 24 days storage period at 4 °C.The results were as follows:(1)GAP could inhibit the growth of L.monocytogenes and S.aureus.And the minimum inhibitory concentrations of GAP against L.monocytogenes and S.aureus both were 0.1 mg/mL.(2)GAP had significant destructive effects on cell morphology and physiological metabolism of the L.monocytogenes.Firstly,the positive charge of GAP could neutralize the negative charge on the surface cell membrane of L.monocytogenes and cause the depolarization of the bacterial cell membrane.Then the interaction between GAP and the cell membrane of L.monocytogenes could increase the permeability of the bacterial membrane,leading to the leakage of intracellular substances such as protein nucleic acid.GAP treatment also led to the DNA damage in L.monocytogenes,resulting in the degradation of bacterial DNA.In addition,GAP decreased the activities of respiratory chain dehydrogenase and the ATPase in L.monocytogenes and inhibited the EMP pathway of the bacteria.(3)GAP exhibited a strong antibacterial activity against S.aureus.GAP severely damaged the membrane of S.aureus,resulting in the leakage and disruption of the bacterial membrane.Meanwhile,phenomena of cell deformation,cytoplasm aggregation and cell wall lysis were observed in GAP-treated S.aureus cells,which demonstrated that GAP destroyed the bacterial cell structure.Moreover,inactivation of NSE and ATPase by GAP inhibited bacterial growth and propagation.The destructive effect of GAP against S.aureus was associated with the membrane disruption and the levels of intracellular oxidative stress in S.aureus by GAP.The stressful environment condition of bacteria treated by GAP could induce ROS production with a dose-dependent manner.And then the produced ROS led to a bacterial oxidative stress response.The low dose ROS could attenuate the injury of cells,and the high dose ROS could destruct the bacterial structures and intracellular mediated functions through degrading and deforming the cellular biomacromolecules(including the proteins and DNA),thereby resulting in the ROS-mediated bacterial apoptosis.(4)The applied effects of GAP on SNS showed that GAP markedly(P < 0.05)increased the hardness,springiness,gumminess and chewiness of SNS and had little effect on the cohesiveness and resilience of SNS.However,these textural parameters did not obviously change during the period of storage.In comparison to the control and 0.2% GAP,0.4 and 0.6% GAP treatment effectively remained the whiteness of SNS after 12 days storage.The values of pH,TVB-N,TBARs and TVC of SNS with GAP were obviously lower than those of the control,especially the higher GAP-does treatment.The overall acceptability scores of SNS with GAP were higher than that of the control.These results indicated that GAP improved the textural properties and retarded the undesirable physiochemical and microbial changes,thus enhancing the quality and extending the shelf-life of SNS.